Electronic memory cards are commonly used for non-volatile storage of digital data in many electronic computing and communication devices. A variety of different card formats are available from various suppliers, such as SanDisk Corporation (Sunnyvale, Calif.). SanDisk, for example, offers Secure Digital (SD™) cards, as well as smaller microSD™ cards, which are designed to be plugged into a compatible receptacle in a host device. Such cards contain flash memory and an embedded processor, which communicates with the host processor using a predefined bus protocol (such as the SD protocol).
A subscriber identity module (SIM) is a type of smart card that is used for authentication of a host device in which the SIM is installed, based on a unique identifier that is stored securely in the SIM. The SIM may also include a memory (such as flash memory or other non-volatile memory) for storing data. The term “SIM card” originally came into use in the specific context of authenticating mobile telephones in Global System for Mobile (GSM) telephone networks, but has now come to refer to any smart card or other electronic component that securely stores a unique identifier for purposes of authentication. In the context of the present patent application, the term “SIM component” is used in this broad sense. For purposes of authentication, SIM components commonly communicate with the host processor using a predefined SIM protocol, such as the ISO 7816 protocol defined by the International Organization for Standardization.